"We are brothers, friends and moreover neighbors in the Mediterranean," the former international pariah said at the end of a two-day visit to Spain, emphasizing "the culture, the blood, the roots that unite" the two countries.

"I am not here to give a general lesson on colonialism. The two banks [of the Mediterranean] have both known invasions," he said in the speech at Madrid's town hall, where he received the keys of the city from conservative mayor Alberto Ruiz-Gallardon.

He later left Madrid's airport aboard his official plane for Tripoli, the Spanish foreign ministry said, ending a European tour that was his most high-profile foreign visit since he began to rebuild bridges with the United States and Europe four years ago.

Gadhafi visited Spain after a trip to Paris dogged by rows over human rights but which netted deals potentially worth 10 billion euros for French firms.

He met late Monday with Prime Minister Jose Luis Rodriguez Zapatero, after which the Madrid government said Spanish firms could see deals with Libya worth more than $17 billion (11.8 billion euros) in the energy, defense, aeronautics, and infrastructure sectors.

Gadhafi also met Tuesday with Spanish business leaders in a vast Bedouin tent he had set up in the grounds of El Pardo palace outside Madrid, the residence of dictator Francisco Franco until his death in 1975, today used for visiting heads of state.

Among the industrialists invited were the heads of oil groups Repsol YPF and Cepsa, gas company Enagas, and Casa, the Spanish affiliate of European aeronautics giant EADS.

On Sunday, construction group Sacyr Vallehermoso said it had created a joint enterprise with the Libyan government to bid for infrastructure contracts worth more than 50 billion euros in Libya, which has seen strong economic growth since U.N. sanctions were lifted in 2003 and a rise in the price of oil.

"Following this visit, the Spanish government feels that enormous possibilities for investments by Spanish firms in Libya will open up," the government statement said.

Zapatero "told Gadhafi of Spain's interest in cooperating to contribute to a future of peace, stability, democracy, justice and prosperity," it said.

The statement made no mention of the thorny question of human rights, which has been largely sidelined during his visit to Spain.

However, the center-left newspaper El Pais said Gadhafi had undertaken "a European tour that discredits the cause of democracy in Africa," and questioned whether he should be treated differently from "the dictator of Zimbabwe Robert Mugabe."

During his five-day trip to Paris last week, Gadhafi faced a barrage of criticism over past links to terrorism and accusations of ignoring human rights.

French President Nicolas Sarkozy argued that since Gadhafi has abandoned the sponsorship of terrorism and the development of illegal weapons, France should encourage him further down the path of international respectability.

Gadhafi's tour, which began with a trip to Lisbon for the December 8-9 EU-Africa summit, concluded Tuesday with a lunch hosted by King Juan Carlos.

He arrived in Madrid following a two-day private visit to Spain's southern Andalucia region.

It was his first official visit to the country. He made a private visit to Spain in 1984, when he briefly met then prime minister Felipe Gonzalez.

© 2007 Agence France-Presse